Fan placement

Discussion in 'General Hardware' started by Nitris, Sep 18, 2003.

  1. Nitris

    Nitris Guest

    Is it better to put the fan in front or in the back, I only have one fan right now for the case.
     
  2. JJB6486

    JJB6486 Retired Mod Political User

    Messages:
    1,207
    Location:
    West Lafayette, IN, USA
    Two fans, One in front sucking air in, one in back pushing air out. If you only have one, another basic 80mm fan is only a couple bucks. Your PC will run cooler.

    JJB
     
  3. LeeJend

    LeeJend Moderator

    Messages:
    5,291
    Location:
    Fort Worth, TX
    But until you spring for the second one put the first in front blowing in. You already have one in the power supply blowing out.
     
  4. Taurus

    Taurus hardware monkey

    Messages:
    3,206
    Location:
    Sacramento, CA
    i disagree. exhausting hot air is more important than throwing cool air into your case. after all, the placement of the exhaust fan(s) is very close to the thing you're trying to keep cool (the cpu) so the hot air will naturally be sucked out. in turn, cool air will find it's way in through the front or anywhere it can and eventually pass by the cpu fan where it will be used.

    otherwise, if you're blowing air into the front of the case and creating a positive pressure of any kind in the case, most of that cool air will just leak back out through any and all gaps it can. and there are plenty, especially on the front of the case which would be a total waste.

    so if i had a case with space for two exhaust fans and two intake fans and i only had two fans, both would go in back. you'd be able to feel the hot air coming out the back.

    in short; exhaust fans in back encourage a more direct and efficient airflow than intake fans in front.
     
  5. Bretenn

    Bretenn Guest

    agree...
     
  6. ming

    ming OSNN Advanced

    Messages:
    4,252
    Location:
    UK
    I think it's better to blow air into the case to cool the pci cards coz they get quite hot, especially the gfx card. Even if the gfx card has a fan already, the air around the HSF is quite hot which you need to get rid off. That's where the fan at the front can help circulate it.
    If possible, leave the side of your case open. Lets more heat out. :)
     
  7. Steely

    Steely OSNN Addict

    Messages:
    71
    Location:
    Wolverhampton, United kingdom
    What about water cooling and alternative methods of cooling? Are there air conditioning units available for PCs?





    Dan
     
  8. ming

    ming OSNN Advanced

    Messages:
    4,252
    Location:
    UK
    There's no air conditioning, but the nearest to that is the peltier cooler. Heavy stuff!!
     
  9. Erbmaster

    Erbmaster Moderator Folding Team

    Messages:
    1,195
    Location:
    Middle Of Nowhere - UK
    In certain case/fan configurations this can reduce the efficiency of
    air-cooling as the air isn't being forced over the hot-spots.
    There is no point putting thought into the cooling process by carefully selecting case fans,
    and their positioning if only to negate the desired effect by opening up the case side.
    Also any drive cooling being performed by the fan at the
    front/base will be lost as the air
    is not being circulated around the device with any degree of pressure.

    If you're gonna have 2 fans....put 1 in the front of yer case at the
    bottom sucking air in, and put another at the top at the rear.
    This will help pull cool air in and expel the heated air (hot air rises, right?.....:p.)
    Alternatively put both at the back, but this won't help with drive cooling
    if your drives are at the front. (most are)
     
  10. Vector_One

    Vector_One Guest

    You absolutely should use it for exhaust. Otherwise you're PSU fan will have to exhaust all the hot air from your case. And that isn't what you really want, in most cases, anyway. Air will flow in the front of the case, even without a fan, due to the natural flow of the air, if you have an exhaust fan. The only reason you'd need an intake fan is for cooling hard drives, or if you don't have very good airflow inside the case, or if you notice your cpu/mobo temps are too high.
     
  11. LeeJend

    LeeJend Moderator

    Messages:
    5,291
    Location:
    Fort Worth, TX
    Well your almost right about exhausting the hot air...

    If you put all of your fans in the rear you develop a pressure drop through the case because the front inlet is restricted. This pressure drop reduces cooling efficiency for everything inside the case and also reduces the volume of air moved by the fans since they now have to pull against a head pressure.

    Also pulling a vacuum at the rear means you will suck air in across all openings like the gap around the HDs. Good for the HD but now preheated air is being injested into the case and across the cpu and video card. Better to pressurize the case with a larger fan in front forcing cool air into the case at a higher pressure (more efficient heat transfer) and then letting the excess pressure bleed out through all opening (like the gaps around the HD).

    I ran thermal testing on about 10 different configurations using the MB/CPU sensors and a digital thermometer and the worst result I saw was adding a HD cooler. It raised case and CPU temperatures so I threw it away.

    The biggest improvement I saw was adding a front case fan and taking a dremel tool to the front cover to enlarge the inlet air openings to a little larger area than the opening in the fan.

    Consider the CPU fan it cools by blowing cooler air on the heatsink. Revberse the fan and HSF becomes almost useless. I tried it once to see what would happen and it almost fried the cpu.
     
  12. napalmnthemorning

    napalmnthemorning Moderator

    Messages:
    721
    Location:
    OREGON
    I just installed a new Pentium IV ATX "NSpire" in today with a cool blue light out the back. My old RaidMax started to make some loud noises so I knew it was time. Too much heat. You want to blow the hot air out definately. Throwing cool air into the motherboard area I would think could cause some serious problems! :eek:
     
  13. jason2slow

    jason2slow Guest

    what if you have 1 fan on top and one on the side, which way should they be blowing?
     
  14. lieb39

    lieb39 Apple lover, PC User

    Messages:
    526
    Location:
    Australia
    I just recently changed my setup. Before I had 1 fan blowing in the front, and two blowing out the back. Cool, but loud. Than last week I got bored and put a hole in the top of my case, and now I have a fan there, blowing out. It's the other can (other than the cpu and gpu fan) thats turned on in the case. And it's running cool and quiet.

    Pics will come later...


    -lieb39